The present invention generally relates to polyphase amplitude detection.
Polyphase amplitude detection is widely used in power electronics but applications in integrated circuits have been limited.
Tuning circuits to cancel process, voltage and temperature variation and to allow continuous tuning/tracking operation of filters and other functions are widely used in integrated circuits.
A significant number of these tuning circuits are based on Gyrators which can be connected to form an oscillator. Techniques to control the amplitude of oscillators have become more complicated as the ratio of power supply voltage to nominal threshold have decreased with advancing process technology. Irrespective of the technology changes, there is a need for improved stability and response time of amplitude control loops.
A typical oscillator will have a port to control the gain of the feedback loop. As the loop gain approaches unity, the system poles move onto the j-omega axis and the system response from port to output amplitude can be described as K/s or a pure integrator. A simple zero-phase feed back network can be used to close such a loop but most full-wave and half-wave circuits have large dominant poles. A good polyphase rectifier operating from a quadrature source will have a much lower ripple and thus a smaller need to filter thus improving the system response and stability. In the case where the amplitude detector is designed to generate the square of the input, a sine squared and a cosine squared will sum to one eliminating almost any need for the filter.
One problem with a standard peak detector is that one input is source followed into a node with a small leaker current to ground plus a parallel capacitor to ground. This approach is sensitive to the frequency being detected because the detected peak erodes as current is pulled from the capacitor.
A general object of an embodiment of the present invention is to provide a polyphase amplitude detector for use in an integrated circuit.
Another object of an embodiment of the present invention is to provide an amplitude detector for detecting the amplitude of each phase of a signal where the number of sinusoids is greater than one and the phase relationship between the signals is offset.
Briefly, and in accordance with at least one of the forgoing objects, an embodiment of the present invention provides an integrated polyphase amplitude detector which includes means to detect the amplitude of each phase of a signal where the number of sinusoids is greater than one and the phase relationship between the signals is offset.